This class or closure to clamp at specific bounds is nice. But I want to
clamp based on runtime values for upper/lower fairly often. A function is
much better for that use.
On Wed, Jul 8, 2020, 11:22 AM Jonathan Fine
Hi All
This is related to discussion https://mail.python.org/archives/list/python-ideas@python.org/thread/KWAOQFS...
In Python, lists don't have a join method. Instead, it's strings that have the join method. Hence we have: >>> ', '.join('abcde') 'a, b, c, d, e'
The intermediate method we can save and store and use again. >>> joiner = ', '.join >>> joiner('fghijk') 'f, g, h, i, j, k'
We can do something similar when clamping, clipping or trimming a value. For example, suppose we want limits on the room temperature, that the thermostat cannot override. >>> aircon_clipper = Clamper(50, 80)
>>> thermostat_temp = 40 >>> target_temp = aircon_temp_clipper(thermostat_temp) >>> target_temp 50
What I like best about this is that the name of the function -- aircon_temp_clipper -- gives the reason for the clipping (or clamping). And this name can be chosen to suit the domain. I also like that it wraps the high and low values (50 and 80) as data used by a method.
Here's an implementation of Clamper.
class Clamper: def __init__(self, lo, hi):
if not lo <= hi: raise ValueError self._lo = lo self._hi = hi
def __call__(self, num): lo, hi = self._lo, self._hi
at_least_lo = (lo <= num) at_most_hi = (hi >= num)
if at_least_lo and at_most_hi: return num elif at_least_lo: return hi elif at_most_hi: return lo else: raise ValueError
If performance is important to you, you could instead use a closure to create a function. This would also allow you to provide a docstring.
I hope this helps at least some of the people some of the time.
-- Jonathan _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/SXECQD... Code of Conduct: http://python.org/psf/codeofconduct/